Grinder mechanism for boiler furnaces and the like



Sept. "16., 1924.

A. LOTZ ET AL GRINDER MECHANISM FOR BOILER FURNACES AND THE LIKE 4 Sheets-Sheet l GMT/add Lni z Charles JDavidaofl/ Filed Aug. 12

I ll l Nb mm iii fifi u mmWi h r n H mm MM MMMWWW WWW Sept. 16 1924. 1,508,562

A, LOT; ET AL GRINDER MECHANISM FOR BOILER FURNACES AND THE LIKE Filed Aug. '12. 1920 "4 Sheets-Sheet 2 (lifted, L022.

J j widsnm/ J Kennel diiofneys Sept. 16 1924.

A. LOTZ ET AL GRINDER MECHANISM FQR BOILER FURNACES AND THE LIKE Fild Aqg- 12. 1920 4 sheet -sheet 's Loki Charles J namidsowilliarn/ J Sept. 16 1924a A. LOTZ ET AL GRINDER MECHANIM FOR BOILER FURNACES AND THE LIKE Filed Aug. 12

Patented Sept. 16,1924.

s ar r;

ALFREDLOTZ', on CHICAGO, ILLiNoIsfonAnLns J- nAvrnsoN,OFMILWAUKEE, Wisconsm, AND WILLIAM J. annnnsacn CHIOAGQILLINOIS,ASSIGNORS, BY'MnsNn ASSIGNMENTS, TO I/IOLOCH COMPANY,

TION OF VVISCONSXN.v

OF KAUZKAUNA, WISCONSIN,-A Conr'onm GRINDER MECHANISM non BOILERIFUB-NACES AND THE LIKE. 1

Application area August 12, 1920. Serial No. 402,991.

To aZZwhom itmag come m: s

Be it known that We, ALFRED Lo'rz,

CHARLES J. DAVlDSON, and WILLIAM J.,1:EN

NEY, citizens of the United States, residing at Chicago, in the county oft look and State of Illinois, Milwaukee, in the county'of M1lw'aukee and, State of Vhsconsin, and at Chicago, in the county of Cook and State of O'ur' invention relates to grinder mecha nism for furnaces and the like and is an im provement over the Patent Number 1,372,652, granted to C. J. Davidson and. William J. Kenney on March 22, 1922. I

Grinders of the general class described, are employed for removing the refuse or non-combustible product from boiler fur na'ces, drying furnaces, orfurnaces of. anyv description and purpose. These grinders are frequently used in conjunction"With, automatic stokers, the arrangement being such that the grinders and the stokers are automatically actuated, the furnace being automatically fired by the stoker and automatically cleaned of refuse by the grinders, In the mounting of grinders of this general class, it is necessary, in order that efficient and proper operation'may be obtained to the end of acquiring maxin'ium perform ance of the furnace, to mount the grinder adjacent the furnace retort, so that, as the 1 volatile gases are burned, the coke is permitted, due to expansion, to spread over the tu'yereplate and reduce to non-combustible refuse or slag. This, therefore, exposes the surface of the grinder adjacentthe retort;

bed to intense heat. e have found that the main obstacle to the successful use of these grinders has been that of maintaining them due to this high temperature of combustion. Depreciation occurs due to burning, cracking and'mechanical difliculties incident to the large expansion and contraction caused by the intense heating. Al-

cooling the grinder have been proposed, the

inadequacy of them has failed to overcome the diiiiculties.

In various experiments, .it has been found by the use of various testing apparatus that,

regardless of the methods of cooling employed, the formation of, air or steam. pockets adjacentthe fire zone area of the grinderis unavoidable so long as the grinder lies in a horizontal plane. Therate'of flow of the cooling medium becomes an insignifis' cant factor as soon as'thetemperature rises, as the creation of steam constantly increases the size of the pocket Which results in fore? ing the discharge levelbelow themouth of the outlet, permitting the upper portion of the grinder to be exposed.

It is the primary object of'the present invention to so arrange the grinder Within. the furnace, that theliottest portion of the grinder, lying adjacent the the ,zone, is in continuous and constant contact With the cooling medium. This is accomplished by mounting the rotatable grinder in a plane, inclined to the horizontal. plane. The air or steam pocketthen fonned is trapped at the upward forward end of the. inclinedv grinder, at which point the outlet. is pro vided. The circulation of the cooling. medium is such that a constant npwardflow is maintained, Which tends to trap all-air or; steam in apart Which. is remote from the fire zone. We believe that We arethe'first to discover that by inclining the. grinder, a. constant contact of the cooling medium. With the surface adjacent the fire zone is obtained, and consequently claimthe same broadly.

In the grinder embodying our invention, the ends are supported-upon opposite. Walls of the furnace for permitting the grinder to rotate. lVhile it is notessential that the grinder rotates in order to embody the important feature of the invention, however, many ad-vantages'are gained in the operation ofthe grinder in having the entire peripheryinadesubject tothe heat of the.

fire bed. 'Onefof the most important. ad- I surface. By havingthe entire body of the, cylinder sub ect substant ally to the same though Various and numerous methods of temperature, local overheating is overcome and the mechanical difiiculti'es incident to vent local overheating of the grinder walls.

A further object is .111 the method of circulating the cooling fluid for effectively cooling the grinder and preventing steam or air pockets from forming. ater is introduced into the grinder so that, with the inclined position thereof, a distinct circulation is created due to two separate tendencies, first the tendency for the cold water to sink due toits greater weight and second the tendency for the hot water to rise due to expansion.

This. circulation includes a downward flow of the relatively cold water along the lower surface of the grinder drum and an upward flow of the heated water along the upper wall of the drum. As the drum re- 'volves each element of the surface comes into contact with. both these streams.

In the accompanying drawings, we have illustrated our invent on as embodied in several forms of boiler furnaces, which are *equipped with both the underfeed and overfeed stokers, and lying in an axis parallel to the retort as 'well as transverse. However, it is apparent that this showing illustrative merely, and many forms and arrange ments may be had.

' In the drawings:

Figure 1 1s a longitudinal vertlcal section of the inclined grinder with a portion of the driving mechanism removed;

Figure 2 is a side elevation of the same;

Figure 8 is a side end view of the same, illustrating the inlet and discharge pipe;

Figure 4 is a detailed view taken on line 4-4: of Figure 1, illustrating the arrangement of the intake and exhaust passages;

v a grinder Figure 5 is a view of the driving of the grinder, illustrating the regulating mechanism employed to intermittently rotate the Figure 6 is an end view of the same, illustrating the regulating disc employed for varying the degree of rotation;

Figure 7 is a detail view of the cover plate employed;

Figure 8 is a longitudinal vertical section of a' furnace wherein is embodied the inclined grinder, illustrating the manner of supporting same;

Figure 9 is a transverse sectional viewof another type of furnace, illustrating the embodiment of the grinder at each side of the retort andthe manner of distributing the fuel over the tuyere plate upon the grinder;

Figure 10 is a longitudinal section of a typical underfeed stoker furnace equipped with our improved grinder mechanism; and

Figure 11 is a transverse view of a side overfeed center cleaned stoker furnace equipped with our improved grinder mechanlsm.

The grinder illustrated in Figures 1 and 2 is particularly adapted to be disposed adjacent the retort of the furnace in a plane inclined to the horizontal, the degree of which depending on the particular adaptation or needs. In this position the grinder is capable of performing efficiently, and

the novelty resides in the fact that the cooling Water is constantly in cont-act with the entire upper surface of the shell, except that portion immediately adjacent the outlet passage. The level is such at this portion, that regardless of the steam, which might tend to form, it is impossible to force the water away from the surface of the grinder immediate the fire Zone.

In this form the grinder comprises a shell 70, the rear end of which is closed off by a trunnion cap 71, the shell beingprovided with a plurality of studs 7 2 arranged about its surface. As shown in Figure 1, the trunnion cap 71 is threaded on the cylindrical shell 70, displacement of the trunnion cap upon rotation of the cylinder being effectively prevented by means of the stud bolt 7 8, which is threaded through the cap 71 and into the shell 70. A gear collar or ferrule is threaded on the opposite end of the cylindrical shell 70, displacement of this collar or ferrule upon rotation of the grinder being prevented by means of a head stud 75 which extends through the collar 74; and shell 70. The gear collar 74. is provided about its periphery with a pair of operating arms 76 and 77, these operating arms being provided with a ring portion at the upper end which loosely engages the collar 74, having a free connection therewith, and at the lower end provided with a depending arm portion which will be described later. These operating arms 7 6 and 7 7 are suitably spaced for the reception of the driving gear 78 therebetween. A key 80 co-operating with suitable keyways in the collar 74 and the advancing or driving gear 78, serves to rigidly secure the gear 78 upon the gear collar 74:. The last mentioned members in reality form part of the automatic advancing mechanism which is to be described hereinafter, but have been here mentioned as they in part form a portion of the head at this end of the grinder. i

As shown in Figure 2, the studs 72 are of stock material, if desired, taper threaded into the grinder shell and may be easily and cheaply renewed. The studs are mounted about the shell 70 to crush the clinkers at difi'erent points successively along the length of the grinder; surface and: tl'ius to: minimize and distribute the effectof this crushing; action to a: complete IBVOlUtlOIl.

of; the: grinder cylinder.

bolts 82, an annular flange projecting inwardly from the disc 81- cooperating;with. The' disc 81'? is provided with suitable. bore: substantially in the center t-hereof 'forthereception: of the endpipe head83$ The inner" end of' the pipe '83 is enlarged thereby providing; a

the interior of the. 811611370.

suitable shoulder which serves as an annular recess to form a stufling. box inwliich is lodged tliepacking 84: Thedisc8'1 is;

provided with. an annular flange 8:5 proj ecting inwardly therefromabout".theb'ore pro.

vided thereimthis flange serving as: a gland for cooperating; with the packing 84 .to form The 1 a tight joint about the pipe'head 83. pipe. head 83 is threadedadjacent.the annular disc 81 for the reception of a: tension ring 86 thereon, which is adapted tobe: threaded up into engagement with anannularbore surrounding the bore provided in Upon threading the tension ring 86, either inwardly or outwardly'upon. the pipe head 83, the compression onthe: packing 84 may be adjustedrto. prevent lealethe disc 81.

age'of water without causing. 'unduerfriction between the rotating. disc' 811' and the stationary pipe head'183. A-set screw87 is pro vided for securely locking. the tension'ring' 86 against incidental displacement.

The pipe head 83. is. cored outto. provide a waterinlet passage 88*therein, the innerend. of this passage being threaded 'totreceive a waterinletipipe 89', theaaxisiofwhich: is-substantially parallel with the axis ofzthe The:v inner. free end: of thepipe 89 is "provided withan elbow 9O whereby the cold. inlet water is-fed intothe bottom of the cylindricalshell 70. It'is to be here noted that the provision made, causes the flow of" the inlet water. to travel; a downward path, first distributing itself; throughout the lower portion of the cylin drical shell andcontacting'with the lower cylindrical shell- 7 0."

wallsbefore rising tothe upper portion.

This insures eflicient cooling throughoutthe Thewater upon heating imme diately rises, coming into contact with the hottest portion of the shell/70, which not beingthehighest point within the shellfper-- Inits the water, by thermo-actionto continue circulating: Thus a. constant and positivecirculation overthe hottest surfaceofthev grinder.

shell 7 O is assured.

passage. 88 byway of an inlet pipe91-which is. threaded into i-the-pipe. head, 83 a as 1 shown 1 in Figure 4.-

A' dischargespipe92 isthreadediinto the.v pipe head 8? and, communicates with. the; dichargepassage 93; as shown; in. igures I andzli Tshe-heatediwater is discharged into. the discharge passage'93 byway of*- the ups wei dly. extending; passage 3 94, the heated tained at. substantially the level 'of: the; outlet passage 94, as'shown in Figure l.- Thus.v

anysteam generatedin'the shell70 and any air fed in with theinlet water will immediately rise 'to the-top. of the shell, which. in. this? case is that. particular: portion .im.-. mediately adjacent the: outlet: passage; 94, from wherezit is instantly vented through the outlet passage; By discharging the water adjacent thertop of' thetshell 70,-the: outletpassage 94exhausts1athe waterrassoon; as it becomes heated. and rises:- to; the; top: of the shell 70.

, The particular arrangement and relation. of the inlet: pipe; 89 and" discharge outlet to the inclined grinder; creates a method lofcooling the grinder. that insures positive: action ofrthe cooling fluid. The'idownward; turned elbow 90, fromlwhich the co'ldiwater; isdischarged into the; interior: of the: grinder, and thedownwardly sloping lower surface of theinterior ofthegrinde-r:cause? a circulationv from: theentire. lower portion to the upper portion; At the rear: end, where the upper: surface. is: lowered, with" respect to. the horizontal; due to. inclining the grinder, thecooling water hasctwoiforces positively moving'it in contact alongithe"; grinders upper surface; until it reaches: the". outlet 94. Theifirst forceis:that of1the cirtculation due to thecoldiwateriemitting from the i inlet 89 and. spreading throughout theii lower area. "The*- second. force; is: that. of: thermo-actio-n; being; establishedby the. hot testl portion of the grinders upper surface: not beingthe highest pfoint;andi hence, as; the water heats up; it tendsito'xriseto the top. The topyinthe present igrinder; isthat" area adjacent the outlet 94,- and is'without the furnace .to. avoid the inevitable result which happens when the fire be'd works forwardtothe front wall of:.the furnace. The circulationbeing:positive,:.there iswino possi bility of? the; flow jumping. from" inlet. to outlet without; first passing: around the entire; interior;

This-fform! of; grinder: may be. advanced; through thegiear 78- in substantially .the manneras-shown inFigures-5, (Sand 7, on in i any preferred manner;

By referringito Figures to: 7, thea'dw vanci-ngon driving gear 78; ZLSxbBfOIB mens tioned," isskeyed to-the collar'74 which is" fixed upon the cylindrical shell 70, so that,

as the gear 78 is driven, the shell 7 0 will in turn rotate. The operating arms 76 and 77 lying oppositelyadjacent the gear 78 are free to revolve upon the collar 74:, these being retained from displacement upon the collar 74 by the integral circumferential flange 74 and the projecting edge of the disc 81. A projection is provided at the outer] end of the pipe head 83 into which is drilled threaded screw holes 83. This end of the cylindrical grinder is provided with a housing or cover member 121 which is adapted to be disposed over the advancing gear 78 and the upper portion of the operating arms 76 and 77. The housing or cover member 121 is semicircular in formation, having the lower part open. The reduced portion 123 formed on the outer end of the cover 121 is provided with a plate 124, the

plate serving as a cover for the front end of the grinder. The hollow bearing boss 125 is centrally formed upon the plate 124 to receive the projecting end of the pipe 83 which forms a loose bearing for the same, thereby permitting the cover to revolve if desired. To the face of the projecting end of the pipe head 83 there is rigidly secured by means of bolts 126 a regulating disc 127 with a notch'arm j 28 extending upwardly. This arm 128, as shown in Figure 6, is notched so that the movement of the cylindrical shell may be regulated if desired. To this end, a regulating finger 129 is pivotally carried by integral lugs 130 of the cover 12-1.,

the finger 129 having a locking detent 131 adapted to engage with the notches. The diametrical ends of the cover 121 are formed with apertured ears or lugs 132, preferably a pair ateach end, so that a regulating or guiding plate 133, arcuated in formation,

may be alternately carried at either end.

Theregulating plate 133 is pivotally car ried by means of the pintle member 134- secured in the ears 132 by a cotter pin, regulating plate 133 being rigidly held in position by the locking bolt 135 threading in the plate 133 and against the cover 131. This provides a ready means of dissembly of the plate 133. The operating arms 76 and 77 are pivotall provided with a gravity pawl 136 which hes adjacent the regulat ing plate 133 with the hook 137 engaging the undersid thereof. A bolt 138 passes through the operating arms 76 and 77 and through a sleeve 139 disposed within the gravity pawl 136. The operating arms '76 and 77 are reciprocally actuated by the usual driving mechanism, a pin riding in the slot 140 at the lower end of the arms, so as to swing thearms in a path of a limited are. As shown in the drawings, the arms 76 and 77 swing in the direction of the arrow, the pawl rides past the regulating plate until the arms reach the limit The degree of advancement of the gear 78 is dependent upon the position of the re gulating finger 129. As shown in Figure 6, the finger 129 is set at O, which indicates that the grinder is not being rotated. This is sometimes desirable, as would be the case where a series of grinders is being driven by a common driving mechanism and it should be necessary to shut down on the running of one unit or so.

It is to be noticed that we have provided means whereby a reversal of the direction of rotation may be had when necessary. In furnaces of the multi-retort type where it is necessary to employa grinder between each retort, the method of burning the fuel requires that the adjacent grinders rotate in opposite direction. In order to allow for this without causing necessary changes in the construction of the-automatic advancing mechanism, the regulating plate 133 is transposedto the opposite diametrical ears 132 and the pawl 136 reversed in position. The pawl 136 will then advance the gear 78 when the operating arms 76 and 7 7 travel in direction opposite to that shown by the up per arrow in Figure 6.

In Figure 8 we have shown embodied in an under feed type of furnace with an inclined grinder and the manner of supporting the same 111 the furnace. rangement of the furnace comprises the rear wall 145, the front wall 146 and the side wall 14-7 with the tuyere block 148 extending parallel thereto. The upper tuyere blocks are disposed in stepped relation to each other in order to provide draft openings which open into the retort. tuyere blocks are in forms of aprons which lie adjacent to and form longitudinal pocle ets between the grinder, so that the refuse may be discharged therethrough on to the dumping doors 149. The rear end of the grinder is rotatably supported in the bearing pedestal 150, suitable carried by the concrete foundation. The; front end of the grinder is similarly supported by the bearing'pedestal 151, also carried} by the concrete foundation at this end. It will be apparent, though, that any form of support may be provided for the ends of the grinder.

The front end of the grinder is projected through the opening in the front end of the furnace with the automatic advancing mech- The ar- The lower anism on the outside, as ispreferred. This end'of the furnaceis closed by a suitable casing 152 having an opening therein to permit the grinder to pass through, and an upper member 153 which slopes slightly to the coal bed, ending in a downwardly 'eX- tending flange 15a to prevent the bed from working back vupon the grinder. It is to be noted that the upper portion of the grinder, free from contact with the fire bed, is that portion adjacent the outlet 94 in which the air or steam is allowed'to accumulate before being exhausted. This portion will be known as the upper portion of th grinder remote'from the fire zone.

In Figure 9 we'have shown our improved grinder mechanism in connection with a typical side underfeedfurnace. In this case the furnace comprises side "walls '96 and 97and "a rear'wall98. The -coal is carried into the furnace 'by'suitab-le feeder mechanism, (not shown), the coal being forced to rise the fulllengthof theretortbythis mechanism.

As the coal rises in the retort, it is flooded onto the firebars 99 "which .are arranged in pairs alternately movingand fixed, the moving fire bars "working transversely to the retort.

Movement of the fire bars 99 'is obtained through suitable rocking bars 100 and 101 which are rocked to and fro by suitable means located outside of the furnace. The transverse movement of the fire bars 99 in addition to carrying the burning fuel to the inside of the furnace, also conveys the clinker and ash down into the longitudinal pocket 102 and 103 extending parallel to the retort, along the opposite sides thereof. The lower portion of the longitudinalpockets 102 and 103 embrace the grinder cylinders 10a and 105, respectively, these grinder cylinders being rotated in proper direction to crush and discharge the vclinkers between the grinder and the skirt portions of the longitudinal pockets 102 and 103, as has been previously described.

Air for supporting combustionenters the stoker'through the opening'in the'bottom of the wind box 106. 'Upon'entering thewind box 106 the air passes upward along each side of the retort and is discharged partly through the openings 107, the remaining air passing through the hollow firebars '99 and is discharged into the auxiliary air boxes 1.08. .Fromthe airboxes108 the air enters the fire through narrow "openings provided between the are bars 99.

Thefurnace shown in Figure 10 :is that of the typical rear underfe'ed 'sto'ker type. Inthis case the clinker and ash are conveyed out into the transverse pocket 110 which ex tends transversely across the retortadja'cent therear wall 111 thereof. lThefgrinder cylind'er 112 is disposed in lower'portion of the transversepocket 110, this cylinder being rotated in the proper direction to crush-and discharge the clinkers between the grinder and the "skirt portions of the transverse pocket 110.

InFigurell wehave shownour improved grinder mechanism in connection with a typical side feed, center-cleaned stoker fur.- nace. In tliis-casetlie coalmagazines or hoppers '114 and 115 are located along the sides ofthe furnace, the coking capacity of the furnace being thereby materially increased, The ,grate bearers 1116 and 117 for supporting the grate 118, being rocked bywa suitable rocking barlnot shown. Theclinkers and other coarse refuse .pass into the pocket 1119 which extends longitudinally between the grates .118 and are ground out from .under the .live coals byaneans of the grinder cylinder .1120 which is embraced by the lower skirt portions ofthe :longitudinal pockets 119. I 1

Various modifications will suggest themselves to those skilledin the art, but we intend that these modifications shall come within the scope and spirit vvof the appended claims.

W's claim:

1. In combination, a furnace, a rotatable grinder for removing therefuse of said furnace, said grinder supportedrin said furnace at an incline to the horizontal plane of said furnace, means for circulating a cooling medium about theinterior of said grinder, the upper portion of said grinder adapted to have continuous contact with said cooling medium. I

2. In combination, a grinder for cleaning furnaces and the like, a member having fluid inlet and outlet passages extending into said grinder, an inlet pipe communicate ing with the outer end of said inlet passage for feeding, water thereinto, an inlet pipe communicating with the inner end of the said inlet passage for feeding said water into the grinder, a dischargepipe for discharging water from said outlet passage, the inner end of said outlet passage opening into said grinder at a .point without said furnace for causing the entire portion ofthe grinder within said furnace to be subjected to a I continuous "flow.

In combination, a grinder for I cleaning furnaces 'andfthe like, a member atone-end of said grinder having -fluid inlet and outlet passages extending into :said jgrindeinfsaid grinder having sa-idi end protected from contact with the fire bed of the furnace, said outlet passage opening into said furnace at said end whereby the level of the fluid about said outlet-is maintained away from said firebed. i 4-1a a ,grinder for cleaning furnaces and the like, substantiallystationary means for feeding cooling water into a rotatab e within the grinder remote from the fire bed.

5. In combination, a grinder for cleaning furnaces and the like, the upper surface of said grinder adapted to besubjected to the heat of the furnace, a member having fluid inlet and outlet passages extending into said grinder, means without said furnace for feeding water into said inlet passage and discharging water from said outlet passage, said inlet passage directing the flow of water to the lower part of the grinder, said outlet passage exhausting water from a level in said grinder where air and steam tends to accumulate, means for maintaining said. level remote from the fire bed.

6. In combination, a grinder for cleaning furnaces and the like, the upper surface of said grinder adapted to be subjected to heat of the furnace and lie in a plane inclined to the horizontal, a member having fluid inlet and outlet passages extending into said grinder, means forfeeding water into said inlet passage and discharging water from said outlet passage, said inlet passage directing the flow in a downward path to allow the water to rise from the lower part of said cylinder to said upper surface whereby tie air and steam formed are forced to move toward said outlet passage.

7. In combination, a grinder for cleaning furnaces, and the like, a member having fluid inlet and outlet passages extending into said cylinder, means for feeding and. discharging water from said passages, the upper surface of said grinder adapted to lie at an incline and with a portion thereof in contact with a fire zone of the furnace, said inlet passage feeding water into said. grinder so that an upward circulation is created, said circulation terminating at a point immediate said upper surface but remote from the fire zone, said outlet passage opening into said point.

8. In combination a furnace, a grinder comprising a hollow cylinder adapted for rotation, said grinder being supported at an incline, closing means at one end of said cylinder forming a bearing closing means at the other end having passages therein for admit-ting and exhausting a cooling medium from said cylinder and adapted to be stationary relative to said cylinder, said exhaust passage opening into the highest point within said inclined cylinder, said point being remote from the fire bed of said furnace and advancing mechanism for rotating said hollow cylinder.

9. The method of cooling a grinder having a cylinder subjectto the heat of a furnace which comprises first inclining the cylinder with respect to the horizontal, next, feeding a stream of cooling fluid in a downward direction to the lower portion so that it tends to flow to the lower end of the inclined cylinder, and finally, removing the heated water which reaches the higher end of the inclined cylinder after ittravels along the upper surface by thermo-action.

10. In, combination, a rotatable grinder for cleaning furnaces and the like comprising a hollow cylindrical shell, a trunnion member forming a cap at one endof said shell, a stationary member projecting into said shell at the opposite end, said station ary member feeding and withdrawing a cooling fluid, a plate member for closing off this end of said shell, said stationary member and plate having relative rotatable movement,a packing ring within said shell and bet-ween said member and said plate, and means adjustably disposed on said member for compressing said packing ring by drawing said. stationary member and said plate together.

11. In combinatioma. grinder comprising, a hollow cylinder adapted for rotation, a cap for closing one end. ofsaid cylinder and forming a bearing therefor, a stationary head member for the opposite end of said cylinder,,said head member provided with means for feeding water into and discharging water from the interior of said cylinder, a gear on said cylinder, loosely mounted operating arms, a pawl member carried by said arms adapted to engage said gear as the arms are actuated, and means limiting the engagement of said pawl member with said gear.

12. In combination, a grinder comprising, a hollow cylinder adapted for rotation, a cap for closing-one end of said cylinder and forming a bearing therefor, a stationary head member for the opposite end of said cylinder, said head member provided with means for feeding and discharging water from the interior of said cylinder, a ratchet gear on said rotatable cylinder, operating arms carrying a pawl member thereon, a loosely mounted member at one end of the cylinder, a detent member carried by said loosely mounted member, a notched plate fixed to said stationary end head adapted for engagement with said detent, means carried by said loosely mounted member for tripping said pawl out of engagement with said ratchet gear for causing a limited predetermined movement to be imparted to said grinder.

13. In a mechanism for periodically advancing a grinder for furnacesand the like, the combination of a grinder comprising, a hollow cylinder, a ratchet gear at one end of said cylinder, loosely mounted operating arms, a pawl carried by said arms, and

a tripping member adapted to have predetermined fixed posit-ion for tripping said pawl out of engz-igement with said gear thereby limiting the advancement of said grinder.

14. I11 a mechanism for periodically advancing a grinder for furnaces and the like, the combination of a grinder comprising, a hollow cylinder, a ratchet gear at one end of said cylinder, loosely mounted operating arms, a. pawl carried by said arms, a tripping member adapted to have a predetermined fixed position for tripping said pawl out of engagement with said gear thereby limiting the advancement of said grinder, and means permitting transposition of said trip-ping member to reverse the advancement of said cylinder. I

15. In combination, a grinder forclean ing furnaces and the like, loosely mounted reciprocating arms at one end of said cylinder, engaging means carried by said arms for rotating said cylinder, and means tripping said engaging means at predetermined points thereby permitting said grinder to periodically rotate.

16. In combination, agrinder adapted to be supported for rotation in a furnace, mechanism for rotating said grinder, control means for predetermining the degree of said rotation, said control means permitting the reverse rotation of a predetermined degree.

17. In combination, a grinder adapted to be supported for rotation in a furnace, mechanism for rotating said grinder, a timing plate on said grinder, and a connection between said plate and said mechanism for imparting rotation of predetermined degrees to said grinder.

18. In combination, arotatable grinder for cleaning furnaces comprising a hollow cylindrical shell, a cap for closing off one end of said shell, a relatively stationary member passing through saidcap, said memher feedinga cooling fluid into and discharging it from said feeder, shoulders on said ca and said members, a. gasket, and means for drawing said member against said cap for compressing said gasket.

19- In combination, a rotatable grinder for cleaning furnaces comprising a hollow cylindrical shell, a stationary member at one end for feeding a cooling fluid into and withdrawing it from said grinder, a cap rigid with said grinder for closing said end, said stationary member passing through said cap, shoulders on said cap and said stationary member, a gasket, and means for compressing said gasketbe-tween said shoulders.

20. The method of cooling with a fluid an'inclined grinder subject to the heat of a furnace which comprises, creating two separate streams of cooling fluid in said grinder, one of said streams flowing along the bottom of said grinder, a second stream to flow along the upper surface of said grinder by thermo action, rotating the grinder so that all parts make contact with both our names this 10th day of August, 1920.

ALFRED LOTZ. CHARLES J. DAVIDSUN. WILLIAM J. KENNEY. 

